Abstract
Homeostatic and reparative functions of the periodontal ligament are most significant in respect to periodontal therapy and transplantation and/or replantation of tooth. Based on our experimental studies and currently published studies, this review article discusses the mechanism of both tissue regeneration and homeostatic function of the periodontal ligament from the viewpoint of periodontal treatment and tooth transplantation. The involvement of cell proliferation, differentiation, growth factors, microenvironment including the guided tissue regeneration, osteogenic progenitor cells, bone morphogenetic protein are discussed. In relation to transplantation or replantation of tooth and periodontal regeneration, we describe the following characteristics of the periodontal ligament; volume of the periodontal ligament attached to root surface of extracted teeth, characteristics of cells in the periodontal ligament, cell constituting the regenerated periodontal ligament, mechanism maintaining a certain width, particularly the function of Malassez's epithelial rests and mechanism of ankylosis.
